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OPERATION DESCRIPTION
WITH GASEOUS FUEL
After activating switch 1, if the thermostats are closed, the voltage
reaches the command and control equipment (LED 2 switches on)
which starts operating. The fan motor is thus switched on (LED 3)
to carry out preventilation of the combustion chamber, at the same
time the air gate control servomotor moves to the opening position
corresponding to the maximum power setting.
At
the
end
of
the
gate
goes
back
to
the
If the ventilation air control pressure switch has found that there is
sufficient pressure, the ignition transformer will start (LED 4) and,
two seconds later, the safety and main gas valves will open (LED
5).
In particular:
•
The main valve is single-stage and slow opening.
•
The safety valve is an ON/OFF valve.
•
The air gate is activated by an electric servomotor. Remember
that when the thermostat stops the burner, the gate is returned
by the servomotor to the closed position.
The flame is detected by the flame control device and allows the
equipment to proceed to the ignition stage with the switching off of
the ignition transformer. Then the servomotor opens the air gate
gradually and the gas throttle up to the maximum set value.
If there is no flame, the appliance shuts down in "safety lock-out"
mode (LED 7) within 3 seconds of the opening of the main valve.
In safety lock-out mode the valves are closed again immediately.
To release the equipment from this safety position, press button 8
on the synoptic panel.
preventilation
stage
the
ignition
flame
position.
9
1 Main switch ON - OFF
2 Power LED
3 Fan LED
4 Transformer ON led
5 2
0006081545_201305
MODULATION OPERATION DESCRIPTION
When the burner is ignited at the minimum flow-rate, if the modula-
tion probe allows it (adjusted to a temperature or pressure which is
greater than that present in the boiler) the air adjustment servomo-
tor begins to operate;
- in a clockwise direction the air flow increases,
- in an anti-clockwise direction the air flow decreases.
causing a gradual increase in the combustion air flow and con-
sequently of the gas, until it reaches the maximum flow setting of
air
the burner. The burner remains in the maximum flow position until
the temperature or pressure is high enough to trip the modulation
probe, which reverses the rotation of the air adjustment servomo-
tor.
Reverse rotation of the servomotor and consequently a reduction in
gas and air flow take place in short time intervals. By this method,
the modulation system tries to bring the amount of heat supplied
to the boiler in line with the heat that the boiler puts out to service.
The modulation probe installed on the boiler measures any request
variation and automatically adjusts fuel and combustion air sup-
ply, by starting the air/gas adjustment servomotor and increasing
or reducing rotation as necessary. If the limit value (temperature
or pressure) at which the stop device is set (thermostat or pres-
sure switch) is reached even with gas supply at minimum level, the
burner is shut down by the device.
When temperature or pressure returns below the shut-down device
tripping value, the burner is activated once again according to the
program described in the previous section.
3
5
2
6
4
GAS
1
8
stage LED
nd
21 / 34
7
ÖL
10
6 1
stage LED
st
7 Appliance shutdown LED
8 Appliance unlock button
9 Fuel fill button
10 Fuel switch
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